It has been a longstanding goal of physicists to develop a means of large scale wireless power transmission through the air along a controlled path. The operative word in this goal is “controlled”, an element which until now has eluded researchers.
It is recognized that a laser beam of suitable wavelength and energy can penetrate through a gas medium over great distances (i.e., in the kilometric range) and will establish a partially ionized trail therethrough which is straight. Pulsed lasers are now available in the Megawatt class and can deliver pulses on the order of femtoseconds (10−15 seconds); that is one quadrillionth, or one millionth of one billionth of a second. For context, a femtosecond is to a second, what a second is to about 31.7 million years.
When generating a plasma channel, each pulse of the laser bombards the atmosphere with a measured amount of photonic energy. When this energy is increase to a certain level, electrons in the atmosphere become disassociated from their atoms, creating an ionized plasma state. Between laser pulses, the electrons begin to return back to their atoms. The integrity of the field is maintained as long as the pulsing frequency of the laser is faster than the relaxation rate of the ionized plasma. Due to the Kerr-lens effect, once the refractive index has been modified, the plasma field has a self focusing effect on the laser beam. This effect reduces the amount of laser power required to maintain the plasmas field.
Unfortunately, current-carrying plasma channels tend to self constrict due to magnetic forces stemming from the current flowing through the plasma. This phenomenon results is known as the “plasma pinch” or “electron spin magnetic pinch”. Upon closing of the plasma channel as a result of the pinch, the current will then follow the path of least resistance to ground which is by its nature unpredictable and dangerous. Clearly, there is a need in the art for a means of obviating and/or compensating for the above adverse phenomena to provide for the bulk transmission of power in a more safe and controlled fashion.
The provision of a method and apparatus for controlled wireless power transfer in atmosphere would have many scientific and industrial applications. For example, a controlled atmospheric conduction path could be used to safely and repetitively control the discharge of lightning strikes before natural breakdown occurs to protect power plants, airports, launch sites, etc. Militarily, such paths can be used to send a current pulse to a distant object (for example, to destroy a target or to disable a target's electronics). Such paths can also find application in the harvesting of energy from the upper atmosphere as described more fully in applicant's co-pending U.S. Patent Application entitled, Charged Particle Induction From Ionosphere to Ground, filed contemporaneously with the instant application and incorporated herein in its entirety by reference. Still further, such a means of power transfer finds application in the bulk power transmission industry itself which is the context in which the subject invention is described herein.
Electric power transmission is the bulk transfer of electrical power (or more correctly energy). A power transmission network typically connects power plants to multiple substations near a populated area. Electric power transmission allows distant energy sources (such as hydroelectric power plants) to be connected to consumers in population centers, and may allow exploitation of low-grade fuel resources such as coal that would otherwise be too costly to transport to generating facilities.
A power transmission network is referred to as a “grid”. Multiple redundant lines between points on the network are provided so that power can be routed from any power plant to any load center, through a variety of routes, based on the economics of the transmission path and the cost of power. Much analysis is done by transmission companies to determine the maximum reliable capacity of each line, which, due to system stability considerations, may be less than the physical or thermal limit of the line.
Usually transmission lines use three phase alternating current (AC), however, high-voltage direct current systems are used for long distance transmission, or some undersea cables, or for connecting two different ac networks. Electricity is transmitted at high voltages (110 kV or above) to reduce the energy lost in transmission.
High voltage direct current (HVDC) is used to transmit large amounts of power over long distances or for interconnections between asynchronous grids. When electrical energy is required to be transmitted over very long distances, it is more economical to transmit using direct current instead of alternating current. Nonetheless, high-voltage direct current lines are also restricted by thermal limits and voltage drops due to resistance.
Based on the above, it is clear that there is a need in the art to reduce reliance on wire-based energy transmission. It is also clear that in order for wireless-based energy transmission to be a viable solution it is critical that the conductive path be stabilized during energy transmission therethrough and that there be provided a means for capturing an errant charge in the event the channel though which it is traveling closes. The methods and apparatus described herein are directed to meeting these important objectives.